Linfield are facing serious punishment from European football chiefs, including heavy fines and a possible ban, after their fans attacked Celtic players with bottles and coins as their tinderbox UEFA Champions League qualifier at Windsor Park erupted into violence.
Police in full riot gear and backed up by dogs rushed onto the pitch after the final whistle as home supporters threw missiles at stewards and PSNI officers standing between them and several hundred Celtic supporters who'd managed to get tickets for the match despite their club's refusal to take up their official allocation.
In a sometimes poisonous atmosphere, there were regular exchanges of abuse between the two sets of fans. And there could be further sanctions against the Belfast and Glasgow clubs over the singing of sectarian songs during the game, which ended in a 2-0 win for the highly-fancied visitors.
Celtic star Leigh Griffiths could also be disciplined after he ratcheted up tensions at the end of the match by tying a Celtic scarf around a Windsor Park goalpost.
He had also made a 5-1 gesture to home fans, a reference to Celtic's wins last season over Rangers, who have close ties with Linfield.
One Linfield fan who ran onto the pitch after the game was arrested. He signalled that he had been trying to get to Griffiths, who had been the target for most of the missile attacks as he took corners in the second half near the most raucous of the Linfield fans in Windsor's South Stand.
Almost unbelievably, however, Griffiths, who had dodged bottles in the first half too, was booked for time-wasting by Spanish referee Alejandro Jose Hernandez after he showed him a Buckfast bottle that had been thrown at him. At the height of the trouble Linfield goalkeeper Roy Carroll, a former Rangers player, pleaded with his team's supporters to stop the violence, but they ignored him.
And Linfield chairman Roy McGivern went onto the running track to urge the fans to calm down before engaging in talks with police and stewards, one of whom appeared to scale a fence to fight hand-to-hand battles with fans.
Last night Supt Norman Haslett from the PSNI paid tribute to, and thanked, what he said was the vast majority of fans from Linfield and Celtic who "behaved impeccably and enjoyed the football match".
He added, however: "Unfortunately there were a small number of incidents which police and other relevant authorities will be reviewing in the days to come."
He also thanked people who had worked together to ensure fans were able to enjoy the football safely.
Questions will undoubtedly be asked about how so many troublemakers were able to get into Linfield's South Stand, which was supposed to be reserved for members and season ticket holders.
And any security review will also focus on how fans were able to smuggle so many bottles into the stadium despite supposedly extensive searches carried out by a private security firm.
During the match a group of Linfield fans sang The Sash and chanted anti-IRA and Bobby Sands slogans, but when they tried to strike up the Billy Boys they were booed by thousands of other home supporters in the ground.
The majority of the Linfield fans also shouted "Out, out, out" and "scum" at the mobs targeting Celtic players, and they claimed that stewards and police weren't doing enough to tackle the missile throwers.
One fan said: "Those animals only come to Linfield games to cause trouble. They are not true supporters of my club."
Belfast-born Chelsea pensioner Sammy Cameron, who was on a visit home from London, was disgusted by what he saw. The ex-serviceman, who wore his distinctive red and black pensioner's uniform, said: "Linfield deserve a lot of credit for their performance on the park. But it was a pity about what happened in the second half thanks to a few loose heads. And the only people who are going to suffer are the club."
Celtic fans sang a song about Linfield manager David Healy, another former Rangers player, calling him a sad Orange b****** and taunted the home supporters with cries of "Are you Rangers in disguise?"
At times it was more like feud-ball than football in parts of the ground and by the end of the 90 minutes Linfield's fighting performance in keeping the score-line down to 2-0 was almost forgotten in a game that had been billed as the mis-match of the day and which had been sponsored by an undertaker's firm and another company that makes memorials for graves.
For several hours before the kick-off security in Belfast was stepped up with hundreds of police officers on duty at flashpoint areas.
Even the Culloden Hotel near Holywood, where the Celtic players were staying, was in lockdown as visitors were turned away. Overhead, a PSNI helicopter hovered above the luxury hotel as the team prepared to leave for Windsor Park under a heavy police escort.
At bridges above the Sydenham bypass and the Westlink, police were on standby and hundreds more officers were positioned along the Boucher Road. It was there that Celtic fans gathered 90 minutes before kick-off.
They'd bought their tickets on the internet but they'd been warned they would be refused admission to the stadium.
However, at lunchtime yesterday, four hours before the kick-off, Linfield issued a statement confirming a badly-kept secret that any away fans with tickets would be accommodated in Windsor Park's Kop Stand, entering the ground via gates on the Boucher Road.
Sections in the Scottish media called the ticketing arrangements a debacle and said there would be regrets about how the situation had been handled after Celtic refused their allocation and Linfield sold tickets online, giving Celtic fans the opportunity to buy them.
The plan to open up part of the ground for the away supporters had been agreed with the police several days ago but news of the deal was held back to discourage more Celtic fans from trying to buy tickets before sales stopped on Thursday afternoon.
However, thousands of other Celtic supporters were content to stay well away from the no-go area that was Windsor Park and watched the game on TVs in pubs in west Belfast, which was festooned with green and white flags, and in a fanzone at Finaghy two miles and just two train stops away from the ground.
At the Devenish pub complex the car park had been turned into a mini-Parkhead where it was estimated that 2,000 Celtic fans saw the match on Ireland's largest big screen, brought all the way from Co Leitrim.
It was the first - and many fans and officials hope the last -encounter here between the blue half of Belfast's big two and the green and white golden boys of Glasgow's Old Firm, a clash that off the park was classed as high risk by police.
It was also a game that Linfield tried to keep news reporters from seeing, saying they would only issue accreditation to bona fide football writers.
"It was almost as if they hoped that sports reporters would turn a blind eye to any trouble at the ground," said one journalist.
Signs outside Windsor had urged supporters to sing only Linfield songs and to respect their opposition, who were playing their first ever game against the Blues.
The match had been due to be played over the Twelfth but the PSNI refused to allow it to go ahead during the tense marching season.
Celtic had claimed they didn't accept their tickets because the safety of their fans couldn't be guaranteed in Belfast.
But the PSNI queried that contention, and a number of Scottish commentators claimed the real reason was that Celtic, who've been fined 10 times in recent years over their fans' behaviour, feared more fines, and perhaps even more stringent sanctions if there were disturbances in Belfast.
Linfield play the return leg of their European fixture in Glasgow next Wednesday.
They've already received 1,500 tickets from Celtic, but it's not clear yet if they'll all be taken up by travelling supporters.